[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 252340
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI MAY 25 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N13W 6N18W 3N30W 4N44W 3N52W.
SCATTERED MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF
THE AXIS BETWEEN 18W-32W. SIMILAR CONVECTION IS WITHIN 180 NM N
OF THE AXIS BETWEEN 32W-40W.

THE GULF OF MEXICO...
LARGE HEALTHY SFC HIGH PRES RIDGE IS SLOWLY SINKING SWD AND
WEAKENING A BIT OFF THE MID-ATLANTIC COAST. THE TIGHT PRES GRAD
ON THE S SIDE OF THE RIDGE IS PRODUCING BRISK WINDS ACROSS THE
REGION...STRONGEST IN THE E GULF WHERE MOST OBS ARE IN THE 20-25
KT RANGE. THIS STIFF FLOW IS ADVECTING LOW TO MID LEVEL CLOUD
STREAMERS FROM THE ATLC WATERS ACROSS THE FL PENINSULA AND THEN
THINNING AS THEY MOVE WWD IN THE GULF. MOSAIC DOPPLER RADAR
DEPICTS LIGHT SCATTERED SHOWERS ASSOCIATED WITH THESE STREAMERS
ON THE E COAST OF FLA...BUT MOST APPEAR TO BE DRYING OUT BEFORE
REACHING THE GULF. THE MORE NOTABLE WEATHER IS IN THE FAR NW
GULF WHERE A SQUALL LINE RUNS FROM W OF HOUSTON ACROSS THE
COASTAL WATERS TO BROWNSVILLE. THIS ACTIVITY IS ASSOCIATED WITH
STRONG DIFFLUENCE ALOFT AND ENHANCED BY LOW-LEVEL INFLOW.
ELSEWHERE IN THE UPPER LEVELS...ABUNDANT DRY AIR EXISTS IN A
CONFLUENT AREA BETWEEN A RIDGE ALONG 93W AND UPPER LOW ABOVE THE
FLA BIG BEND. LOOKING AHEAD THRU THE WEEKEND...THE SFC RIDGE IS
EXPECTED TO SLOWLY WEAKEN IN PLACE ALLOWING THE ELY TRADES TO
GRADUALLY RELAX.

THE CARIBBEAN SEA...
UNLIKE THE WINDY CONDITIONS IN THE GULF...BROAD SFC TROUGHING IS
PRODUCING A WEAK PRES GRAD IN THE CARIB WITH TWO SFC TROUGH AXES
BEING ANALYZED IN THE REGION. ONE IS IN THE NW CARIB RUNNING
FROM HONDURAS TO NW CUBA. THERE IS A FAIR AMOUNT OF LOW TO MID
LEVEL CYCLONIC TURNING ABOUT THE AXIS...BUT BASED ON SFC OBS IT
DOES NOT APPEAR CLOSED. THE OTHER...MORE SUBTLE...TROUGH AXIS IS
IN THE SW CARIB EXTENDING FROM PANAMA TO 13N80W. IN THE MID AND
UPPER LEVELS...A BROAD TROUGH COVERS MUCH OF THE WRN HALF WITH A
ROUGH AXIS EXTENDING FROM THE WRN TIP OF CUBA TOWARD PANAMA.
EXTENSIVE SWLY UPPER FLOW E OF THE AXIS IS MOISTENING THE
ATMOSPHERE ACROSS MUCH OF THE REGION BETWEEN 68W-82W. THE
COMBINATION OF THIS UPPER FLOW AND LOW-LEVEL CONVERGENCE ALONG
THE SFC BOUNDARIES AND THE ITCZ IS GENERATING SCATTERED SHOWERS
AND ISOLATED TSTMS N OF 18N W OF 73W AND SCATTERED MODERATE
CONVECTION S OF 14N E OF 81W.

THE ATLANTIC OCEAN...
A 1028 MB HIGH PRES SYSTEM IS CENTERED OFF THE U.S. MID-ATLANTIC
COAST NEAR 35N74W. FARTHER E...A STALLED FRONT ENTERS THE AREA
NEAR 32N51W AND EXTENDS SW ALONG 24N61W THEN AS A SFC
TROUGH...LACKING THERMAL GRADIENT...TO 20N67W. A TIGHT PRES GRAD
REMAINS IN PLACE BETWEEN THESE FEATURES PRODUCING 20-30 KT NE TO
E WINDS ACROSS THE SW ATLC. LOW-LEVEL LIFT NEAR THE FRONT ALONG
WITH GOOD DIFFLUENCE ALOFT...JUST E OF AN UPPER JET AXIS RUNNING
FROM THE NRN BAHAMAS EWD TO 28N60W THEN NEWD BEYOND 32N54W...IS
GENERATING SCATTERED SHOWERS WITHIN 240 NM EITHER SIDE OF THE
FRONT AND GENERALLY S OF 28N ELSEWHERE. DRY AIR ALOFT COVERS THE
REGION N AND W OF THE JET AXIS KEEPING THE ATMOSPHERE RATHER
STABLE WITH ONLY A LOW-LEVEL STRATOCUMULUS DECK.

THE SFC PATTERN IN THE CENTRAL AND EASTERN ATLC IS DOMINATED BY
A 1030 MB HIGH CENTERED NEAR THE NWRN AZORES. THIS HIGH IS
PRODUCING MODERATE TRADES ACROSS THE REGION GENERALLY S OF 23N.
IN THE UPPER LEVELS...A MASSIVE UPPER TROUGH EXTENDS FROM THE
THE IBERIAN PENINSULA SWWD ACROSS THE CANARY ISLANDS TO 23N40W.
A BROAD FLAT UPPER RIDGE IS CENTERED IN THE DEEP TROPICS WITH
THE RIDGE AXIS RUNNING FROM W AFRICA NEAR 12N15W TO 8N39W.
A STRONG 110-130 KT UPPER JET HAS SET UP BETWEEN THESE FEATURES
EXTENDING FROM 20N36W TO THE AFRICAN COAST NEAR 22N16W.
HOWEVER...LITTLE SIGNIFICANT MOISTURE IS ASSOCIATED WITH ANY OF
THESE UPPER FEATURES. IN FACT...OUTSIDE OF THE ITCZ...WIDESPREAD
FAIR WEATHER IS THE RULE.

$$
CANGIALOSI


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